The dumbing down of American is most evident in the slow decay of substantive content in the enormously influential media, the 30 second sound bites (now down to 10 seconds or less), lowest common denominator programming, credulous presentations on pseudoscience and superstition, but especially a kind of celebration of ignorance.
As a source of innovation, an engine of our economy, and a forum for our political discourse, the Internet can only work if it's a truly level playing field. Small businesses should have the same ability to reach customers as powerful corporations. A blogger should have the same ability to find an audience as a media conglomerate.